Select tag & options for select 101

Question

Can someone explain me how this exactly works ?

Problem:

I have a Scaffold and run the migration:

rails g migration AddRarityToTags rarity:string

For the rarity input i need a dropdown displaying a list of options to select from.

e.g. Rarity = Free
              Common
              Rare
              Epic

If i'm right i need something like this:

  select_tag :rarity, options_for_select(@rarity)

I searched a lot but it didn't helped much, i got more confused.

Can someone help me out ?

Answer 1

Imagine putting the raw options into the tag as a string:

select_tag :rarity, '<option>Free</option><option>Common</option>...'

That's what options_for_select returns, if you pass in an array:

select_tag :rarity, options_for_select(['Free', 'Common', ...])

See: http://api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html#method-i-options_for_select

To enforce the "dumb views" rule, and to let others use that array, you can move it to the model:

class Tag < ActiveRecord::Base

  RARITY_LEVELS = %w(Free Common Rare Epic)

end

...

select_tag :rarity, options_for_select(Tag::RARITY_LEVELS)

Both me and the OP would like to know if Rails, or any gems, let us get any DRYer than this; if, for example, Rails lets us attach the RARITY_LEVELS directly to the rarity field...